1. Field of the Invention
The present invention relates to improvements in a brazed-plate-fine type heat exchanger, and more particularly to a counter-flow type heat exchanger.
2. Description of the Prior Art
Hitherto a heat exchanger as shown in FIG. 16 of the drawing of the present application has been proposed and disclosed, for example, in Japanese Utility Model Provisional Publication No. 63-49189. This conventional heat exchanger is provided with a plurality of tube elements 52 defining a first passage 61 for low-temperature fluid A and a housing 56 defining a second passage 62 for high-temperature fluid B by surrounding the tube elements 52. The low-temperature fluid A flows through the tube elements 52 from inlet ports 54 to outlet ports 55 in the direction indicated by arrows of FIG. 16. The high-temperature fluid B flows through the second passage 62 such that the flowing direction of the fluid B is perpendicular to that of the fluid A to implement the heat transmission therebetween. That is, the heat exchanger is so called a cross-flow type. Accordingly, such a conventional brazed-plate-fine type and cross-flow type heat exchanger has a restriction in the improvement of the heat transmission coefficient. Furthermore, due to a clearance 51 between the tube elements 52 and a side plate 58 in this conventional heat exchanger, a substantial amount of the high-temperature fluid B flows through the clearance 51 and therefore the heat transmission between the high-temperature fluid B and the low-temperature fluid A is not effectively implemented.